PAPER CONTAINER SEAL HEATING METHOD AND SEAL HEATING APPARATUS

Abstract: This invention relates to a seal heating method and a seal heating apparatus for heating a seal portion of an opened end part, in order to fold and heat-bond an opened end part at a creased top end part or bottom end part during a paper container assembling operation. Out of opened end parts (1a, 1b) of a paper container (1), an inner seal portion (30a) is opposed to an inner circumferential surface heating element, and an outer seal portion (30b) to outer circumferential surface heating elements (4, 5, 6, 7, 13, 14, 15, 16). At least the inner circumferential surface heating element (8, 17) is swung on its axis so as to vary the positions on the inner seal portion (30a) upon which the hot air ejected from hot air ejection ports (8a) of the inner circumferential surface heating element (8) impinges. This enables a seal portion (30) of the paper container (1) to be heated uniformly and excellently.

Description: Technical Field The present invention relates to a seal heating method for a paper container and apparatus for heating seal portions of open edge portions such as a top edge portion and a bottom edge portion so as to bond the open edge portions and assemble a paper container. Related Art Generally, closed paper containers which is filled with liquid such as soft drink and alcoholic drink have been widely used. The paper container is formed in the following manner. A plane paper material is folded in a cylinder shape to form the paper container. A bottom edge portion of the container is heated by a heating apparatus. Next, the bottom edge portion is folded along fold lines, and then the heated portion is press-bonded so as to form a bottom portion. Thereafter, the paper container is filled with a predetermined liquid. A top edge portion which has fold lines is headed by the heating apparatus, and then the folded portion of the top edge portion is press-bonded. Thus, the content of the paper container is sealed. According to JP3-25463, the conventional heating apparatus which heats the edge portions of the paper container comprises a plane side heating portion, a folded side heating portion, and a hexagonal inner peripheral heating portion. The plane side heating portion heats two flat sides of the top edge portion of the container. The folded side heating portion heats two folded sides with fold lines of the top edge portion. The hexagonal inner peripheral heating portion heats entire inner walls of the top edge portion. Many hot sir blowing small holes are formed at predetermined portions of the flat side heating portion, the folded side heating portion, and the inner peripheral heating portion. Thus, hot air is blown from the many hot air blowing small holes to predetermined portions of the front and rear surfaces of the top edge portion. Thus, according to the conventional heating apparatus, since hot air is blown from each hot air blowing small hole, the top edge portion of the paper container is locally heated. When the paper container is composed of a laminate of resin, aluminum foil, paper, resin, and so forth, since the aluminum has high heat conductivity, it easily diffuses heat. However, when the temperature of hot air is high, foams, burns, or pin holes will take place on the heated portion of the container. When the paper container is composed of a laminate of resin, glass evaporation layer, paper, resin, and so forth, since the glass evaporation layer has low heat conductivity, the portion exposed to hot air is locally heated. At this portion, foams, burns and pin holes tend to take place. In addition, since positions of the four inner corners of the top edge portion of the container vary for each paper container due to the difference of size and fold lines. Thus, the amount of hot air blown to the four inner corners varies for each paper container. In this case, when the material is folded and pressed, seal defects will take place and thereby the content will leak out from the paper container. Likewise, such problems take place in an apparatus which has many hot air blowing small holes blowing hot air to the bottom edge portion of the paper container. Disclosure of the Invention The present invention is done from the above-described point of view. An object of the present invention is to provide a seal-heating method for a paper container and apparatus of the same, for press-bonding the top edge portion or the bottom edge portion with hot air blown from hot air blowing small holes without occurrences of foams, burns, and pin holes and for equally and properly heating portions in the vicinity of four inner corners of the edge portions. A first aspect of the present invention is a seal-heating method for a paper container by using a seal-heating apparatus, comprising the steps of facing an inner seal portion of a seal portion formed at an open edge portion of a cylindrically shaped paper container which has not been assembled to an inner peripheral heating portion of the seal-heating apparatus and facing an outer seal portion of the seal portion to an outer peripheral heating portion of the seal-heating apparatus, and blowing hot air from hot air blowing small holes formed at the inner peripheral heating portion to the inner seal portion and blowing hot air from hot air blowing small holes formed at the outer peripheral heating portion to the outer seal portion, characterized in that the inner peripheral heating portion is oscillated. A second aspect of the present invention is a seal-heating apparatus for a paper container, for seal-heating a cylindrically shaped paper container, comprising an inner peripheral hating portion oscillatably disposed, facing to an inner seal portion of a seal portion formed at an open edge portion of the paper container which has not been assembled and having hot air blowing small holes from which hot air is blown to the inner seal portion, an outer peripheral heating portion facing to an outer seal portion of the seal portion and having hot air blowing small holes from which hot air is blown to the outer seal portion, characterized by an oscillating device for oscillating the inner peripheral heating portion. According to the first aspect of the present invention, since the inner peripheral heating portion is oscillated, the direction of the hot air blown from the hot air blowing small holes can be varied so as to prevent the hot air from directly flowing to the inner seal portions. Thus, the inner seal portions can be equally, fully, and properly heated. According to the second aspect of the present invention, since the inner peripheral heating portion is oscillated by the oscillating device, the direction of hot air blown from the many hot air blowing small holes formed in the inner peripheral heating portion can be varied so as to prevent hot air from flowing to limited points of the inner seal portions. Thus, the entire inner seal portions can be equally and properly heated. Brief Description of Drawings Fig. 1 is a schematic diagram for explaining a paper container seal heating method and apparatus according to an embodiment of the present invention; Fig. 2 is a front view showing a seal heating apparatus for a top edge portion according to the embodiment of Fig. 1; Fig. 3 is a front view showing principal portions of a seal heating apparatus for a bottom edge portion of a paper container; Fig. 4 is a schematic diagram showing the seal hating apparatus for the bottom edge portion; Fig. 5A is a schematic diagram showing an oscillating device; Fig. 5B is a schematic diagram showing another oscillating device; Fig. 6 is an overall perspective view showing a conventional paper container; Fig. 7 is a perspective view showing a paper container in which body portions have been raised before assembled; Fig. 8 is a perspective view showing the top edge portion of the paper container that has been folded before assembled and heated; and Fig. 9 is a schematic diagram showing the seal heating apparatus for the top edge portion of the paper container. Best Modes for Carrying out the Invention For easily understanding the function of the present invention, first of all, a conventional seal-heating method for a paper container and apparatus of the same will be described. Generally, as a closed paper container which is filled with soft drink or alcoholic drive, for example a paper container 1 shown in Fig. 6 has been used. The paper container 1 is formed in a cylinder shape as shown in Fig. 7. First, an open edge portion 1a of the paper container 1 is heated by a seal-heating apparatus. Next, the edge portion 1a is folded along fold lines 2, and then the heated portion is press-bonded. Thus, a bottom portion of the paper container 1 is formed. Next, as shown in Fig. 8, the paper container 1 having the bottom portion is filled with a desirable liquid. Thereafter, an open top edge portion 1b of the paper container 1 which has fold lines 3 is heated by the seal heating apparatus. Next, the top edge portion 1b is folded and the press-bonded. Thus, the paper container 1 as shown in Fig. 6 is formed. Conventionally, as a heating apparatus that heats the open edge portions of the above-described paper container 1, a seal heating apparatus for a top edge portion as shown in Fig. 9 has been used. The seal heating apparatus for the top edge portion comprises flat side heating portions 4 and 5, folded side heating portions 6 and 7, and a hexagonal inner peripheral heating portion 8. The flat side heating portion 4 and 5 heat the flat sides of the top edge portion 1b of the paper container 1. The folded side heating portions 6 and 7 heat the two folded sides with fold lines of the top edge portion 1b. The hexagonal inner peripheral heating portion 8 heats the inner walls of the top edge portion 1b. The shape of the hexagonal inner peripheral heating portion 8 corresponds to the shape of the top edge portion 1b with the fold lines. The flat side heating portions 4 and 5, the folded side heating portions 6 and 7, and the inner peripheral heating portion 8 have many hot air blowing small holes 4a, 5a, 6a, 7a, and 8a, respectively. The hot air blowing small holes 4a, 5a, 6a, 7a, and 8a blow hot air to predetermined portions of the front and rear surfaces of the top edge portion so as to heat the top edge portion 1b. The present invention is an improvement of such a paper container seal-heating method and apparatus. Next, with reference to Figs. 1 to 5, the present invention will be described in detail. In the following description, the same portions as those shown in Figs. 7 to 9 are depicted by the same reference numerals and their detail description will be omitted. Fig. 1 is a schematic diagram for explaining a seal-heating apparatus for a top edge portion of a paper container. Fig. 2 is a front view showing principal portions including the seal-heating apparatus. In Figs. 1 and 2, reference numeral 1 represents a paper container. Reference numeral 1b represents a top edge portion. Reference numerals 4 and 5 represent flat side heating portions. Reference numerals 6 and 7 represent folded side heating portions. Reference numeral 8 represents an inner peripheral heating portion. Reference numeral 10 represents a chamber portion of the seal heating apparatus. The seal-heating apparatus comprises the flat side heating portions 4 and 5, which heat two flat sides of the top edge portion 1b, the folded side heating portions 6 and 7, which heat two folded sides having fold lines of the top edge portion 1b, the hexagonal inner peripheral heating portion 8, which heats the entire periphery of the inner walls of the top edge portion 1b and whose shape corresponds to the shape of the top edge portion 1b with the fold lines, and the chamber portion 10, which accommodates the heating portions 4, 5, 6, 7, and 8. The chamber portion 10 accommodates the heating portions 4, 5, 6, 7, and 8, as mentioned above, and is coaxially lowered to and raised from the paper container 1 so that the chamber portion 10 covers the top edge portion 1b of the paper container 1 and is separated therefrom. The operation of the chamber portion 10 with respect to the paper container 1 can be performed by relatively moving the paper container 1 and the chamber portion 10. Thus, it should be noted that the top edge portion 1b of the paper container 1 may be raised and lowered with respect to the chamber portion 10. Hot air heated at a predetermined temperature is supplied from a hot air supply portion (not shown) in an apparatus main body 10a, and then is blown from the hot air blowing small holes 4a, 5a, 6a, 7a, and 8a of the flat side heating portion 4 and 5, the folded side heating portions 6 and 7, and the inner peripheral heating portion 8 to predetermined positions of the top edge portion 1b. In other words, seal portion 30 to be bonded are formed at the open top edge portion 1b of the paper container 1. The seal portion 30 are composed of inner seal portion 30a and outer seal portion 30b. The inner seal portion 30a are formed on an inside surface of the top edge portion 1b. The outer seal portions 30b are formed on an outside surface of the top edge portion 1b (see Figs. 1 and 8). When the chamber portion 10a is placed on the top edge portion 1b, the outer seal portion 30b faces to the flat side heating portions 4 and 5 and the folded side heating portions 6 and 7. The inner seal portion 30a faces to the inner peripheral heating portion 8. The flat side heating portions 4 and 5 and the folded side heating portions 6 and 7 compose outer peripheral hating portions. The hot air blowing small holes 4a, 5a, 6a, 7a, and 8a are small round holes with diameters ranging from 0.4 mm to 2 mm and formed at pitches of 1 mm to 10 mm. If necessary, the hot air blowing small holes 4a, 5a, 6a, 7a, and 8a may be formed in a plurality of rows. According to the present invention, the inner peripheral heating portion 8 having the hot air blowing small holes 8a can be oscillated. In other words, as shown in Fig. 1, the inner peripheral heating portion 8 can be oscillated on the plane perpendicular to the center axial line of the inner peripheral heating portion 8 with an oscillating angle ranging from around 0.3 deg. to 10 deg. The inner peripheral heating portion 8 is oscillated by a first oscillating portion 19 or 20 shown in Fig. 5A. In other words, the inner peripheral heating portion 8 is oscillated in arrow directions by the first oscillating portion 19 or 20. The inner peripheral heating portion 8 is pivoted by a shaft portion 25. The first oscillating portion 19 or 20 is connected to the outer peripheral side of the inner peripheral heating portion 8. The first oscillating portion 19 has a slider crank mechanism. One edge of a link rod 22 of the slider crank mechanism is pivoted to an outer peripheral portion of a disc 21 of the slider crank mechanism that is rotated. The other edge of the link rod 22 is pivoted to the outer peripheral portion of the inner peripheral heating portion 8. Thus, the inner peripheral heating portion 8 can be oscillated in the arrow directions in accordance with the rotation of the disc 21 (Fig. 5A). The other first oscillating portion 20 has a linear reciprocal moving mechanism that is driven by a solenoid. An edge portion of a drive lever 24 of the linear reciprocal moving mechanism connected to a solenoid main body 23 is pivoted to an outer peripheral portion of the inner peripheral heating portion 8. By an electric operation of the solenoid main body 23, the drive lever 24 is reciprocally moved. Thus, the inner peripheral heating portion 8 is oscillated in the arrow directions (Fig. 5A). It can be understood that either the first oscillating portion 19 or 20 may be used. In addition, another oscillating operating means may be used. The period of the oscillating movement of the inner peripheral heating portion 8 is in a range from 1 Hz to 20 kHz. Thus, as denoted by a single-dotted line of Fig. 1, the direction of the hot air blown from the hot air blowing small holes 8a of the inner peripheral heating portion 8 periodically varies. Consequently, the area of hot air blown from the hot air blowing small holes 8a is enlarged. In addition, the hot air can equally and properly heat the enlarged area. As a result, even if the paper container has a glass evaporation layer, it can be properly heated. Hitting position of the inner seal portion 30a against which the hot air blown from the hot air blowing small holes 8a hits, is moved in a straight locus. In particular, the hot air is equally and properly blown to four inner corners 9 of the paper container 1. The oscillating operation of the inner peripheral heating portion 8 is not limited to the above-described one in which the hitting position of the inner seal portion 30a is moved in a straight locus. Instead, the hitting position of the inner seal portion may be moved in a circle locus or an oval locus. In other words, as shown in Fig. 5B, the inner peripheral heating portion 8 may be oscillated not only about the axial line 0 thereof, but also about an perpendicular line P perpendicular to the axial line O. In this case, the inner peripheral heating portion 8 is oscillated about the axial line O by the first oscillating portion 27. In addition, the inner peripheral heating portion 8 is oscillated about the perpendicular line P perpendicular to the axial line O by a second oscillating portion 28. The first and second oscillating portions 27 and 28 are connected to a control device 29. The first and second oscillating portions 27 and 28 are controlled by the control device 29. The control device 29 controls a moving amount X of the hitting position of the inner seal portion 30a against which the hot air hits in the case that the inner peripheral heating portion 8 oscillates about the axial line O. At the same time, the control device .29 controls a moving amount Y of the hitting position of the inner seal portion 30a against which the hot air hits in the case that the inner peripheral heating portion 8 oscillates about the perpendicular line P. For example, when the moving amount X = γ sin  and the moving amount Y = γ cos , the hitting position of the inner seal portion 30a against which the hot air from the hot air blowing small holes 8a hits, is moved in a circular locus. Likewise, the hitting position of the inner seal portion 30a may be moved in an oval locus. The first and second oscillating portions 27 and 28 compose an oscillating device. The flat side heating portions 4 and 5 and the folded side heating portions 6 and 7 may be oscillated in the same manner as the inner peripheral heating portion 8. Next, with reference to Figs. 3 and 4, a seal heating apparatus for a bottom edge portion 1a of the paper container 1 will be described. The heating process of the bottom edge portion 1a is performed in the condition that the paper container 1 is not filled with the content (juice, liquor, or the like). The bottom edge portion 1a can be sealed in a cylinderically shaped state that the bottom edge portion 1a do not have fold lines. In other words, a chamber portion 12 of a seal-heating apparatus 12a is lowered to the bottom edge portion 1a (denoted by a single-dotted line) which is held by a mandrel 11 so that the bottom edge portion 1a is covered by the chamber portion 12. In this state, the bottom edge portion 12 is heated. After the heating process is completed, the chamber portion 12 is raised and thereby the heating process is completed. When the seal heating process is performed, it is necessary to relatively move the paper container 1 and the chamber portion 12. Thus, it is possible to raise and lower the bottom edge portion 1a of the paper container 1 so that the bottom edge portion 1a is inserted into and separated from the chamber portion 12. The heating chamber portion 12 for the bottom edge portion 1a is shown in Fig. 4. Referring to Fig. 4, the heating chamber 12 accommodates a pair of first flat side heating portions 13 and 14, a pair of second flat side heating portions 15 and 16, and an inner peripheral heating portion 17. The first flat side heating portions 13 and 14 have many hot air blowing small holes 13a and 14a, respectively. The second flat side heating portions 15 and 16 have many hot air blowing small holes 15a and 16a, respectively. The inner peripheral heating portion 17 is formed in a rectangular shape, and has many hot air blowing small holes 17a. As with the seal heating apparatus for the top edge portion 1b of the paper container 1, the inner peripheral heating portion 17 is oscillated by oscillating devices similar to those shown in Figs. 5A and 5B. Thus, the direction of hot air blown from the many hot air blowing small holes 17a of the inner peripheral heating portion 17 can be varied, thereby fully and equally heating predetermined portions of the bottom edge portion 1a. In particular, hot air is fully and equally blown to four inner corners 18 of the bottom edge portion 1a as with other portions thereof. Modifications of the seal heating apparatus for the bottom edge portion 1a, substitute means thereof, and modifications thereof are similar to those of the seal heating apparatus for the top edge portion 1b. Thus, their description will be omitted. As described above, according to the seal heating method for a paper container of the present invention, the inner seal portions of the open edge portion of the cylindrically shaped paper container are faced to the inner peripheral heating portion. The outer seal portions are faced to the outer peripheral heating portions. As at least, the inner peripheral heating portion is oscillated, hot air brown from the many hot air blowing small holes formed on the inner peripheral heating portion diffuses to the inner seal portions of the paper container, thereby equally heating the inner seal portions. Thus, the hot air equally hits to four inner corners of the paper container, thereby equally heating the inner seal portions to be bonded. In addition, the hot air blown from the hot air blowing small holes does not flow to narrow areas. Instead, the hitting position against which the hot air hits, can be moved. Thus, foams, burns, and pin holes due to spot heating can be prevented. In addition, since the seal portions to be bonded can be equally heated, seal defects can be prevented. Consequently, the paper container can be prevented from being broken and therefore the leaking of the content can be prevented. Moreover, the seal-heating apparatus for a paper container of the present invention comprises the inner heating portion and outer peripheral heating portions. The shape of the inner peripheral heating portion corresponds to that of the inner seal portions of the cylindrically formed paper container. The shape of the outer peripheral heating portions corresponds to the shape of the outer seal portions of the paper container. The many hot air blowing small holes are formed in the inner peripheral heating portion and the outer peripheral heating portions. Hot air heated at a predetermined temperature is blown from the hot air blowing small holes to the seal portions of the paper container. As at least the inner peripheral heating portion can be oscillated by the oscillating device, the direction of the hot air blown from the hot air blowing small holes of the inner peripheral heating portion is varied. As a result, the hot air can be prevented from being blown to narrow areas. In addition, since the hot air is equally blown to four inner corners of the paper container, they can be equally heated. Thus, foams, burns, and pin holes due to spot-heating can be prevented. Moreover, since seal defects due to insufficient heating is prevented, the paper container can be prevented from being broken and the leaking of the content can be prevented. Since the apparatus according to the present invention is constructed by simply providing the oscillating device, the cost of products can be reduced. Industrial Utilization The present invention can be applied for all technical fields of all the containers filled with substance, particularly containers filled with liquid such as soft drink or alcoholic drink.

Claims: A seal-heating method for a paper container by using a seal-heating apparatus, comprising the steps of: facing an inner seal portion (30a) of a seal portion (30) formed at an open edge portion (1a, 1b) of a cylindrically shaped paper container (1) which has not been assembled, to an inner peripheral heating portion (8, 17) of the seal-heating apparatus, and facing an outer seal portion (30b) of the seal-portion (30) to an outer peripheral portion (4, 5, 6, 13, 14, 15, 16) of the seal-heating apparatus; and blowing hot air from hot air blowing small holes (8a, 17a) formed at the inner peripheral heating portion (8, 17) to the inner seal portion (30a), and blowing hot air from hot air blowing small holes (4a, 5a, 6a, 7a, 13a, 14a, 15a, 16a) formed at the outer peripheral heating portion (4, 5, 6, 7, 13, 14, 15, 16) to the outer seal portion (30b), characterized in that the inner peripheral heating portion (8, 17) is oscillated. The seal-heating method as set forth in claim 1, wherein the inner peripheral heating portion (8, 17) is oscillated about the axial line thereof. The seal-heating method as set forth in claim 2, wherein the inner peripheral heating portion (8, 17) is oscillated with an oscillating angle ranging from 0.3 deg. to 10 deg. The seal-heating method as set forth in claim 2, wherein the inner peripheral heating portion (8, 17) is oscillated at a period ranging from 1 Hz to 20 kHz. The seal-heating method as set forth in claim 2, wherein the inner peripheral heating portion (8, 17) is further oscillated about a perpendicular line perpendicular to the axial line thereof. The seal-heating method as set forth in claim 5, wherein the inner peripheral heating portion (8, 17) is oscillated about both the axial line thereof and the perpendicular line perpendicular to the axial line thereof so as to move in a circular locus hitting position of the inner seal portion (30a) against which hot air from the hot air blowing small hole (8a, 17a) of the inner peripheral heating portion (8, 17) hits. The seal-heating method as set forth in claim 5, wherein the inner peripheral heating portion (8, 17) is oscillated about both the axial line thereof and the perpendicular line perpendicular to the axial line thereof so as to move in an oval locus hitting position of the inner seal portion (30a) against which hot air from the hot air blowing small hole (8a, 17a) of the inner peripheral heating portion (8, 17) hits. A seal-heating apparatus for a paper container, for seal-heating a cylindrically shaped paper container, comprising: an inner peripheral heating portion (8, 17) oscillatably disposed facing to an inner seal portion of a seal portion 30 formed at an open edge portion (1a, 1b) of the paper container (1) which has not been assembled and having hot air blowing small holes (8a, 17a) from which hot air is blown to the inner seal portion (30a); an outer peripheral heating portion (4, 5, 6, 7, 13, 14, 15, 16) facing to an outer seal portion (30b) of the seal portion (30) and having hot air blowing small holes (4a, 5a, 6a, 7a, 13a, 14a, 15a, 16a) from which hot air is blown to the outer seal portion (30b); characterized by an oscillating device (19, 20, 27, 28) for oscillating the inner peripheral heating portion (8, 17). The seal-heating apparatus as set forth in claim 8, wherein said inner peripheral heating portion (8, 17) is oscillatable about the axial line thereof, and wherein said oscillating device includes a first oscillating portion (19, 20, 27) for oscillating said inner peripheral heating portion (8, 17) about the axial line thereof. The seal-heating apparatus as set forth in claim 9, wherein said inner peripheral heating portion (8, 17) is further oscillatable about a perpendicular line perpendicular to the axial line of said inner peripheral heating portion, and wherein said oscillating apparatus includes a second oscillating portion (28) for oscillating said inner peripheral heating portion (8, 17) about the perpendicular line perpendicular to the axial line thereof. The seal-heating apparatus as set forth in claim 10, further comprising a control device (29) connected to said first and second oscillating portions (27, 28), wherein the control device (29) controls the first and second oscillating portions (27, 28) so as to move in a circular or oval locus hitting portion of the inner seal portion (30a) against which hot air from the hot air blowing small holes (8a, 17a) of the inner peripheral heating portion (8, 17) hits.

Inventors: OKUSHITA MASATAKA, OKUSHITA, MASATAKA, OKUSHITA, MASATAKA DAI NIPPON PRINTING CO., LTD.
Applicants: DAINIPPON PRINTING CO LTD, DAI NIPPON PRINTING CO., LTD.
Application year: 1994
Main classification: B65B51
IPC codes: B65B7, B31B1, B31B3, B65B51, B29C65, B29C35